On Mon, Apr 9, 2018 at 5:21 PM, Caio Marcelo de Oliveira Filho < caio.olive...@intel.com> wrote:
> Hi, > > > >> Question: nir_deref_instr_get_variable will walk the deref instr > > >> chain, but does it even make sense if there's a array or struct in > > >> this deref chain? Should this be asserted? > > >> > > > > > > That's an interesting question. Certainly, at this point in the patch > > > series, we can't make that assumption. This is because we haven't > checked > > > the mode yet. However, once we can assume deref instructions, we can > check > > > the mode and then go on to find the var. Maybe something like this > > > (untested): > > > > > > https://gitlab.freedesktop.org/jekstrand/mesa/commit/ > > > 33aee39955eff842d6ea263da2f36e60287e62ee > > > > > > > It turns out that there is one system value which is an array: > > gl_SampleMask. However, due to details, we only ever load element 0 so > we > > can ignore the array deref in that case. Unfortunately, this means that > we > > can't do any better than what we have here. :-( > > I think we could still be strict while handling that case, by being > explicit about it in the middle of the patch you shared: > > nir_deref *deref = nir_src_as_deref(load_deref->src[0]); > if (deref->mode != nir_var_system_value) { > continue; > } > > if (deref->deref_type != nir_deref_type_var) { > assert(deref->deref_type == nir_deref_type_array); > assert(nir_instr_get_variable(deref)->data.location == > SYSTEM_VALUE_SAMPLE_MASK); > /* Short explanation that we only load ever position zero, maybe > even assert... */ > deref = nir_deref_instr_parent(deref); > } > > assert(deref->deref_type == nir_deref_type_var); > nir_variable *var = deref->var; > > Would something like that work? > I took another swing at it, and this one seems to make Jenkins happy: https://gitlab.freedesktop.org/jekstrand/mesa/commit/ad3cc9f301da3519d4f76767a6d9e98e5a5c118e
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